While the game does put an interesting spin on the first-person shooter, the ridiculous oversights and design flaws of the adventure component stifle what fun there is to be had.

WARP's Enemy Zero is essentially two games in one: a spooky inventory-based adventure game and a first-person shooter with a twist - invisible enemies. Even in the midst of combat, your only means of targeting your opponent is by way of a sonic tracking system that beeps in varying pitch and frequency to inform you of the enemy's location. Unfortunately, the adventure component of the game is riddled with arbitrary puzzles that cheapen the game's potentially creepy genre hybrid.

A hostile and invisible alien life-form has penetrated the spaceship Aki, whose crewmembers' state of suspended animation is abruptly cancelled by the ship's emergency program. As Laura Lewis, you awaken, disoriented, faced with the task of establishing contact with your crewmates across the vast and lonely space vehicle and investigating the nature of its invisible terror. Whenever you're in individual rooms, crewmans' quarters, locker rooms, labs, etc., the game is run in search mode, a largely cinema-driven adventure style of play, with all the lag time and frustrating control issues that you expect from cutscene-driven gaming. Push the D-pad, and wait to see if the Saturn notices and moves the camera. In this mode you are essentially free from harm, as no alien interaction ever takes place while you're in search mode - in other words, there's no combat engine. Whenever you're crawling around the hallways and mazes between the individual rooms of the ship, you're in action mode, which is a much more dangerous first-person shooter-style mode.

In either mode, Enemy Zero has a great horror vibe. The eerie music, created by Michael Nyman, is reminiscent of darker themes from TV's the Twilight Zone and sets the lonesome and creepy mood of the game. The adventure aspect of the game is especially dark. Mild gore and gruesome black comedic touches reinforce the sense of dread - picking up a deceased crewmember's disembodied hand and keeping it in your inventory for use on a DNA lock may have set a new standard in tastelessness.

For the most part, gameplay in Enemy Zero's adventure component is of the "stand in predetermined locations pushing the action button to see if anything happens" variety (read: Myst), with a healthy dose of good old-fashioned put-stuff-in-places-style gameplay, in which the objects imply solutions before you're even faced with anything puzzling; for example, here's a key, so you better go find a door that's locked. Many of the game's puzzles are frustrating and arbitrary, and some feel more like design flaws than tests of logic or wits. All too often you're trapped in a room, not by monsters or locked doors, but by a bizarre or unexplained inability to leave - in the final scene on Disk One you even exit through the door of a crewmember's room, only to be treated to a cutscene of turning right back around and reentering the room with no explanation. This same scene requires that the same two videophone calls be made upwards of a dozen times, eliciting identical responses from the receiving end until, on try number 15 or so, a different response occurs and you're finally allowed to leave the room. There's no rhyme or reason to it, and there's no logical excuse for puzzles that require mindless repetition like this.

The invisibility of your alien opponents makes the game's first-person shooter element an unusual one. You locate your enemy by means of three simple tones. A high-pitched tone indicates that the enemy is somewhere in front of you. A midranged tone indicates that it is flanking you. A lower tone indicates that it is behind you. The number of beeps per second indicates the distance between you and your enemy. This sounds easy enough, but takes considerable adjustment in real combat. It's especially challenging because your energy gun cannot immediately fire; you must hold down the fire button and wait for a charge to build up before blasting, and if you hold it for too long, the energy disperses with no shot fired. Precise timing is required, especially given the energy gun's short range. To that end, the game comes with a practice program that begins with visible simulated opposition and gradually takes off the training wheels. While this whole beeping business sounds a little silly at first, especially since it interferes with the tried-and-true "rocking out with the home stereo" technique of video game mastery, it actually adds a lot to the game's sense of being hunted and the general horror movie vibe.

While Enemy Zero does evoke a fairly potent sense of dread, in the end it was the awkward snags in gameplay that I was dreading. More often than not, either the puzzles were too simple - like when the elevator isn't working and one of the switches in the power room down the hall is off - or completely random - like making the same videophone call 15 times before being allowed to leave a room. While the game does put an interesting spin on the first-person shooter, the ridiculous oversights and design flaws of the adventure component stifle what fun there is to be had.